This is the release version with all debug stuff thrown out -- in return

I have heavily commented the code, so maybe someone else besides me
culd get the hang of this programm.

1 files changed, 95 insertions, 107 deletions

diff --git a/core/opiealarm/opiealarm.c b/core/opiealarm/opiealarm.c
index d96ffaf..70e5415 100644
--- a/core/opiealarm/opiealarm.c
+++ b/core/opiealarm/opiealarm.c
@@ -1,12 +1,12 @@
-/* opiealarm.c
+/*
+ * opiealarm.c
+ *
 *  This program is for extracting the event time/date out
 *  of /etc/resumeat and setting the RTC alarm to that time/date.
-*  It is designed to run via a script just before the iPaq
-*  is suspended.
-* 
-*  Roughly based on ipaqalarm from Benjamin Long
+ *  It is designed to run via a script just before the iPAQ
+ *  is suspended and right after the iPAQ resumes operation.
 *
-*  written by Robert Griebl <sandman@handhelds.org>
+ *  written and copyrighted by Robert Griebl <sandman@handhelds.org>
 */
 
 #include <stdio.h>
@@ -28,8 +28,6 @@
         #define PIDFILE "/var/run/opiealarm.pid"
         #define APMFILE         "/proc/apm"
 
-FILE *log; // debug only
-
 int resume ( int resuspend );
 int suspend ( int fix_rtc );
 int main ( int argc, char **argv );
@@ -37,49 +35,28 @@ int fork_with_pidfile ( void );
 int kill_with_pidfile ( void );
 void remove_pidfile ( void );
 void usage ( void );
-void sig_handler ( int sig );
-void error_msg_and_die ( int perr, const char *msg );
+void sig_handler_child ( int sig );
+void sig_handler_parent ( int sig );
 int onac ( void );
 
 static int opiealarm_was_running;
+static pid_t parent_pid = 0;
 
-static pid_t startpid = 0;
 
 
-void log_msg ( const char *msg )
-{
-        if ( log ) {
-                fprintf ( log, msg );
-                fflush ( log );
-        }
-}
-
-void error_msg_and_die ( int perr, const char *msg )
+void sig_handler_child ( int sig )
 {
-        if ( perr )
-                log_msg ( strerror ( errno ));
-        log_msg ( msg );
-
-        if ( getpid ( ) != startpid ) 
-                kill ( startpid, SIGUSR1 );
-
-                while ( 1 )     // pretend we are waiting on RTC, so opiealarm -r can kill us
-                sleep ( 1 );
-}
-
+        // child got SIGUSR2 -> cleanup pidfile and exit
 
-void sig_handler ( int sig )
-{
-        if ( log ) {
-                log_msg ( "GOT SIGNAL -> EXITING\n" );
-                fclose ( log );
-        }
         remove_pidfile ( );
         exit ( 0 );
 }
 
 void sig_handler_parent ( int sig )
 {
+        // parent got SIGUSR1 -> safe to exit now
+
+                parent_pid = 0;
         exit ( 0 );
 }
 
@@ -101,6 +78,11 @@ int fork_with_pidfile ( void )
         pid = fork ( );
         
         if ( pid > 0 ) {
+                // We can not just exit now, because the kernel could suspend 
+                // the iPAQ just before the child process sets the RTC.
+                // Solution: just wait for SIGUSR1 - the child process will 
+                // signal this when it thinks it is safe to exit.
+                
                 signal ( SIGUSR1, sig_handler_parent );
                 while ( 1 )
                         sleep ( 1000 );
@@ -111,8 +93,10 @@ int fork_with_pidfile ( void )
                 return 0;
         }
 
-        signal ( SIGTERM, sig_handler );
-        signal ( SIGINT,  sig_handler );
+        // child process needs to react to SIGUSR2. This is sent when
+        // a new opiealarm process is started.
+
+        signal ( SIGUSR2, sig_handler_child );
 
         // save pid
         if (( fp = fopen ( PIDFILE, "w" ))) {
@@ -138,21 +122,25 @@ int kill_with_pidfile ( void )
 {
         FILE *fp;
         pid_t pid;
+        int res = 0;
+
+        // terminate a running opiealarm child process
+        // return 1 if we really killed one
 
         if (( fp = fopen ( PIDFILE, "r" ))) {
                 if ( fscanf ( fp, "%d", &pid ) == 1 )
-                        return ( kill ( pid, SIGTERM ) == 0 ) ? 1 : 0;
+                        res = ( kill ( pid, SIGUSR2 ) == 0 ) ? 1 : 0;
                 fclose ( fp );
         }
-        return 0;
+        return res;
 }
 
 void remove_pidfile ( void )
 {
-        unlink ( PIDFILE );
+        // child is about to exit - cleanup
         
-        signal ( SIGTERM, SIG_DFL );
-                signal ( SIGINT,  SIG_DFL );
+                unlink ( PIDFILE );
+        signal ( SIGUSR2, SIG_DFL );
 }
 
 
@@ -195,19 +183,24 @@ int main ( int argc, char **argv )
         if ( !mode )
                 usage ( );
 
+
+        parent_pid = getpid ( );
+
         // kill running opiealarm
-        startpid = getpid ( );
         opiealarm_was_running = kill_with_pidfile ( );
         remove_pidfile ( );
 
         switch ( mode ) {
-                case 'r': return resume ( ac_resusp );
+                case 'r': opt = resume ( ac_resusp );
+                          break;
                 case 's':
-                default : return suspend ( fix_rtc );
-        }
-        return 0;
+                default : opt = suspend ( fix_rtc );
+                          break;
         }       
                 
+        parent_pid = 0;
+        return opt;
+        }       
 
 
 int suspend ( int fix_rtc )
@@ -223,95 +216,79 @@ int suspend ( int fix_rtc )
         if ( !fork_with_pidfile ( ))
                 return 3;
                 
-        log = fopen ( "/tmp/opiealarm.log", "w" ); 
-        log_msg ( "STARTING\n" );
+        // we are the child process from here on ...
+
+        tzset ( );  // not sure if it is really needed -- it probably doesn't hurt ...
         
+        do { // try/catch simulation
 
+                // read the wakeup time from /etc/resumeat
         if (!( fp = fopen ( "/etc/resumeat", "r" ))) 
-                error_msg_and_die ( 1, "/etc/resumeat" );
+                        break; //  ( 1, "/etc/resumeat" );
         
         if ( !fgets ( buf, sizeof( buf ) - 1, fp ))
-                error_msg_and_die ( 1, "/etc/resumeat" );
+                        break; //  ( 1, "/etc/resumeat" );
 
         fclose ( fp );
         
-        alrt = atoi ( buf );
-        
+                alrt = atoi ( buf ); // get the alarm time
         if ( alrt == 0 )
-                error_msg_and_die ( 0, "/etc/resumeat contains an invalid time description" );
-        
+                                break; //  ( 0, "/etc/resumeat contains an invalid time description" );
                 alrt -= 5; // wake up 5 sec before the specified time
-
-
-                if ( log )
-                fprintf ( log, "Setting RTC alarm to %d\n", alrt );
-
-        tzset ( );
-        
         alr = *gmtime ( &alrt );
 
-        // get system time
-        time ( &syst );
+                time ( &syst );// get the UNIX system time
                 sys = *localtime ( &syst );     
                 
-        // Write alarm time to RTC
-        if (( fd = open ( "/dev/misc/rtc", O_RDWR )) < 0 )
-                        error_msg_and_die ( 1, "/dev/misc/rtc" );
+                if (( fd = open ( "/dev/misc/rtc", O_RDWR )) < 0 )  // open the RTC device
+                                break; //  ( 1, "/dev/misc/rtc" );
                 
-        // get RTC time
-        memset ( &rtc, 0, sizeof ( struct tm ));
+                memset ( &rtc, 0, sizeof ( struct tm ));    // get the RTC time
         if ( ioctl ( fd, RTC_RD_TIME, &rtc ) < 0 )
-                        error_msg_and_die ( 1, "ioctl RTC_RD_TIME" );   
+                                break; //  ( 1, "ioctl RTC_RD_TIME" );  
         rtct = mktime ( &rtc );
 
-        fprintf ( log, "System  time: %02d.%02d.%04d %02d:%02d:%02d DST: %d (TZ: %s, offset: %d)\n", sys. tm_mday, sys. tm_mon + 1, sys. tm_year + 1900, sys. tm_hour, sys. tm_min, sys. tm_sec, sys. tm_isdst, sys. tm_zone, sys. tm_gmtoff );
-        fprintf ( log, "RTC     time: %02d.%02d.%04d %02d:%02d:%02d DST: %d (TZ: %s, offset: %d)\n", rtc. tm_mday, rtc. tm_mon + 1, rtc. tm_year + 1900, rtc. tm_hour, rtc. tm_min, rtc. tm_sec, rtc. tm_isdst, rtc. tm_zone, rtc. tm_gmtoff );
-        fprintf ( log, "Wakeup  time: %02d.%02d.%04d %02d:%02d:%02d DST: %d (TZ: %s, offset: %d)\n", alr. tm_mday, alr. tm_mon + 1, alr. tm_year + 1900, alr. tm_hour, alr. tm_min, alr. tm_sec, alr. tm_isdst, alr. tm_zone, alr. tm_gmtoff );
-
-        fprintf ( log, "System/RTC diff: %d seconds\n", (  syst - rtct ) - sys. tm_gmtoff );
+                rtc_sys_diff = ( syst - rtct ) - sys. tm_gmtoff;  // calculate the difference between system and hardware time
 
-
-        rtc_sys_diff = ( syst - rtct ) - sys. tm_gmtoff;
-        
-        if ( fix_rtc && (( rtc_sys_diff < -4 ) || ( rtc_sys_diff > 4 ))) {
+                if ( fix_rtc && (( rtc_sys_diff < -3 ) || ( rtc_sys_diff > 3 ))) {
                 struct tm set;
-                
                 set = *gmtime ( &syst );
         
-                fprintf ( log, "Correcting RTC: %d seconds\n", rtc_sys_diff );
+                        // if the difference between system and hardware time is more than 3 seconds,
+                        // we have to set the RTC (hwclock --systohc), or alarms won't work reliably.
 
             if ( ioctl ( fd, RTC_SET_TIME, &set ) < 0 )
-               error_msg_and_die ( 1, "ioctl RTC_SET_TIME" );
+                       break; //  ( 1, "ioctl RTC_SET_TIME" );
         }
 
-        // set alarm time
-        if ( ioctl ( fd, RTC_ALM_SET, &alr ) < 0 )
-                        error_msg_and_die ( 1, "ioctl RTC_ALM_SET" );   
-                // enable alarm irq
+                if ( ioctl ( fd, RTC_ALM_SET, &alr ) < 0 )  // set RTC alarm time
+                                break; //  ( 1, "ioctl RTC_ALM_SET" );  
         if ( ioctl ( fd, RTC_AIE_ON, 0 ) < 0 )
-                error_msg_and_die ( 1, "ioctl RTC_AIE_ON" );
+                        break; //  ( 1, "ioctl RTC_AIE_ON" );   // enable RTC alarm irq
         
-        if ( log )
-                fprintf( log, "SIGUSR: pid %d - SLEEPING: pid %d\n", startpid, getpid ( ));
-        kill ( startpid, SIGUSR1 );
+                // tell the parent it is safe to exit now .. we have set the RTC alarm
+                kill ( parent_pid, SIGUSR1 );
                         
-        // wait for alarm irq
-        if ( read ( fd, buf, sizeof( unsigned long )) < 0 )
-                error_msg_and_die ( 1, "read rtc alarm" );
+                if ( read ( fd, buf, sizeof( unsigned long )) < 0 ) // wait for the RTC alarm irq
+                        break; //  ( 1, "read rtc alarm" );
         
-        log_msg ( "WAKEUP\n" );
+                // iPAQ woke up via RTC irq -- otherwise we would have received a SIGUSR2
+                // from the "resume instance" of opiealarm.
         
-        // disable alarm irq
-        if ( ioctl ( fd, RTC_AIE_OFF, 0 ) < 0 ) 
-                error_msg_and_die ( 1, "ioctl RTC_AIE_OFF" );
+                if ( ioctl ( fd, RTC_AIE_OFF, 0 ) < 0 )     // disable RTC alarm irq
+                        break; //  ( 1, "ioctl RTC_AIE_OFF" );
                 
         close ( fd );
         
-        log_msg ( "EXITING\n" );
+                remove_pidfile ( ); // normal exit
+                        return 0;
         
-        fclose ( log );
-        remove_pidfile ( );
+        } while ( 0 );
+        
+        kill ( parent_pid, SIGUSR1 );  // parent is still running - it can exit now
         
+                while ( 1 )         // pretend that we are waiting on RTC, so opiealarm -r can kill us
+                sleep ( 1000 ); // if we don't do this, the "resuspend on AC" would be triggerd
         return 0;
 }
 
@@ -321,6 +298,8 @@ int onac ( void )
         FILE *fp;
         int on = 0;
 
+        // check the apm proc interface for AC status
+
         if (( fp = fopen ( APMFILE, "r" ))) { 
                 int ac = 0;
         
@@ -338,30 +317,38 @@ int resume ( int resuspend )
 
         // re-suspend when on AC (optional) when woken up via RTC
 
-        if ( !opiealarm_was_running ) { // opiealarm -s got it's RTC signal -> wake up by RTC
+        if ( !opiealarm_was_running ) { 
+                // if opiealarm -s didn't wake up via RTC, the old process gets killed
+                // by kill_by_pidfile(), which is recorded in opiealarm_was_running
+        
                         if ( resuspend && onac ( )) {
                         time_t start, now;
                         char *argv [4];
                                                 
                         if ( !fork_with_pidfile ( ))
                                 return 4;
-                        kill ( startpid, SIGUSR1 );
 
-                        // sleep <resuspend> sec (not less!)
+                        // we can't wait for the resuspend timeout in the parent process.
+                        // so we fork and tell the parent it can exit immediatly
+                                
+                        kill ( parent_pid, SIGUSR1 );
+
+                        // sleep <resuspend> seconds - this method is much more precise than sleep() !
                         time ( &start );
                         do {
                                 sleep ( 1 );
                                 time ( &now );
                         } while (( now - start ) < resuspend );
 
-                        if ( onac ( )) { // still on ac
-                                // system() without fork
+                        if ( onac ( )) { // still on ac ?
                                 argv[0] = "qcop";
                                 argv[1] = "QPE/Desktop";
                                 argv[2] = "suspend()";
                                 argv[3] = 0;
         
                                 // hard coded for now ...but needed
+                                // another way would be to simulate a power-button press
+                                
                                 setenv ( "LOGNAME", "root", 1 );
                                 setenv ( "HOME", "/root", 1 );
                                 setenv ( "LD_LIBRARY_PATH", "/opt/QtPalmtop/lib", 1 );
@@ -369,6 +356,7 @@ int resume ( int resuspend )
                         
                                 remove_pidfile ( );
                         
+                                        // no need for system() since this process is no longer usefull anyway                  
                                 execv ( "/opt/QtPalmtop/bin/qcop", argv );
                                 
                                 perror ( "exec for qcop failed" );